Residence time of water film and slug flow features in fuel cell gas channels and their effect on instantaneous area coverage ratio

Lorenzini-Gutierrez, Daniel; Kandlikar, Satish G.; Hernández-Guerrero, Abel; Elizalde‐Blancas, Francisco

doi:10.1016/j.jpowsour.2015.01.041

Cited by 35 publications

(33 citation statements)

References 32 publications

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“…To analyze the liquid water removal characteristics, a control volume with the size of L cvx × L cvy (= 5 mm × 5 mm) is defined. In addition to the rectangular channel, the trapezoidal channels are considered following the several investigations which paid attention to the merits of the trapezoidal cross-sectional shape for a PEM fuel cell GC [11][12][13][14]18]. In Figure 1b …”

Section: Computational Domainmentioning

confidence: 99%

“…In Figure 1a, the rectangular channel cross section (REC configuration) has a width of 0.7 mm and a height of 0.4 mm. This channel geometry is proposed by Owejan et al to meet the enhanced performance targets of the United States Department of Energy for automotive fuel cells [18,21]. An entrance length of = 7 mm is used to allow the incoming air flow from the inlet to form a fully developed velocity profile before interacting with an initially patched liquid water slug with a length of = 3 mm.…”

Section: Computational Domainmentioning

confidence: 99%

“…In addition to the geometry of the GCs, the effect of GDL and channel wall wettability is critical to the two-phase flow patterns [16][17][18][19][20][21]. Turhan et al [16] investigated the effect of channel wall wettability on through-plane liquid water distribution in a PEM fuel cell via high resolution neutron imaging.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the hydrophilic channel may result in a higher pressure drop at higher water flow rates although film flow patterns induced by the hydrophilic channel provide stable water and air flow distribution. Lorenzini-Gutierrez et al [18] studied the effects of channel cross-sectional geometry, channel surface wettability, and superficial air velocity on the liquid water film and slug flow features in straight GCs with the five different shapes of channel cross section. To find a suitable balance between a hydrophobic surface which reduces the surface tension forces and a hydrophilic surface which promotes top wall film flow and a clear GDL surface, a range of hydrophilic contact angles for the top and side channel walls were compared together with a fixed hydrophobic GDL surface contact angle of 140 • .…”

Section: Introductionmentioning

confidence: 99%

“…The temporal evolution of gas-liquid interface, the WVF, and the WCR of the GDL surface are presented to describe the slug and film flow characteristics inside the bent GCs. Although Lorenzini-Gutierrez et al investigated the effects of channel cross-sectional geometry [18], only the straight GC geometry was considered and the effect of channel surface wettability was studied only for the rectangular cross-sectional geometry. In contrast, this work investigates on how the presence of the corner section in the bent GCs can affect the liquid water removal characteristics by inspecting a control volume located in the corner section of GCs.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Liquid Water Dynamics in Bent Gas Channels of a Polymer Electrolyte Membrane Fuel Cell with Different Channel Cross Sections in a Channel Flooding Situation

2017

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Abstract:The transport characteristics of water slugs in a bent gas channel of a polymer electrolyte membrane (PEM) fuel cell are numerically studied using the volume of fluid (VOF) method. To investigate the effects of channel cross-sectional shape in a channel flooding situation, the gas channels (GCs) with one rectangular and two trapezoidal cross sections are compared. Parametric studies are also conducted to evaluate the effects of the contact angle of the top and side walls, the contact angle of the gas diffusion layer (GDL) surface, and the air inlet velocity. Considering both of the water volume fraction (WVF) and GDL water coverage ratio (WCR), the trapezoidal channel with open angles of 60 degrees provides the most favorable performance in a channel flooding condition. Among all the top and side wall contact angles considered, the hydrophobic contact angle of 120 degrees shows the best results. Among the three GDL contact angles of 90, 110 and 140 degrees, the hydrophobic GDL contact angle of 140 degrees provides the most favorable water removal characteristics in a channel flooding situation. For all cross-sectional shapes, the water removal rate increases and the liquid water interface shows more complex patterns as the air inlet velocity increases.

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Section: Computational Domainmentioning

confidence: 99%

Section: Computational Domainmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Comparison of Liquid Water Dynamics in Bent Gas Channels of a Polymer Electrolyte Membrane Fuel Cell with Different Channel Cross Sections in a Channel Flooding Situation

2017

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Numerical investigation of drop dynamics in presence of wettability gradient inside a serpentine channel of proton exchange membrane fuel cell

Malhotra

Ghosh

2020

Int J Energy Res

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Summary Water management significantly affects the performance of a proton exchange membrane fuel cell (PEMFC). Therefore, interest is felt to numerically investigate water droplet movement and slug formation inside the microchannel (gas) of PEMFC. Two important parameters—water coverage ratio and pressure drop have been studied in detail. A U‐shaped geometry with a round corner is used for this purpose. 3D unsteady‐state models are used to study the drop dynamics using commercial CFD software ANSYS FLUENT 18. For tracking of water drop dynamics, the volume of fluid model is used. Two different situations are simulated. In the first case, the investigation of hydrodynamics of the 0.4 mm drop adhered to the surface of the gas diffusion layer (GDL) has been done. In the second case, simulation of air‐water slug flow has been done. GDL surfaces at upstream and downstream of bend are modified using user‐defined functions, such that the GDL surface has a dynamic contact angle with respect to the direction of flow. This makes it a continuously hydrophilic surface at upstream and continuously hydrophobic surface at downstream with respect to the direction of flow. The impact of GDL wettability on water retention and removal has been discussed. It is noted that the presence of a gradient facilitates the removal of water drop adhered to the GDL surface. For the case of a suspended drop with an increase of 1°/mm in the magnitude of the gradient, a decrease of 30% is observed in water coverage ratio and pressure drop observed in the channel. Such modified surfaces aids in the conversion of slugs to film at the downstream of bend that reduces maldistribution. The pressure fluctuations and average pressure drop are reduced by 66% when subjected to the aforementioned hybrid gradient.

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A Slope Right‐angle Turn Applied in the Flow Channel Promotes Water Management in Proton Exchange Membrane Fuel Cells

et al. 2018

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Effective water removal and transport in the flow field is significantly important to the critical water management in proton exchange membrane fuel cells (PEMFCs). In this work, a slope turn was proposed in the hydrophobic channel of the multi‐serpentine flow field, and the transport and dynamics of water in the modified flow channel were numerically investigated with the volume‐of‐fluid method. The simulation results indicated that, with the presence of the slope turn, the water droplet can be effectively detached from the surface of the gas diffusion layer although the channel walls are hydrophobic. Meanwhile, the hydrophobic channel walls are beneficial to decrease interfacial resistance of water transport, avoiding water accumulation in the flow channel. The wall contact angle, slope angle and gas flow velocity are three important factors which significantly affect water behavior and pressure drop in the flow channel. For considered cases in this work, the appropriate wall contact angle, slope angle, and gas flow velocity were proved to be 140°, 110°, and higher than 2 m s−1, respectively.

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Residence time of water film and slug flow features in fuel cell gas channels and their effect on instantaneous area coverage ratio

Cited by 35 publications

References 32 publications

Comparison of Liquid Water Dynamics in Bent Gas Channels of a Polymer Electrolyte Membrane Fuel Cell with Different Channel Cross Sections in a Channel Flooding Situation

Comparison of Liquid Water Dynamics in Bent Gas Channels of a Polymer Electrolyte Membrane Fuel Cell with Different Channel Cross Sections in a Channel Flooding Situation

Numerical investigation of drop dynamics in presence of wettability gradient inside a serpentine channel of proton exchange membrane fuel cell

A Slope Right‐angle Turn Applied in the Flow Channel Promotes Water Management in Proton Exchange Membrane Fuel Cells

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